Equilibrium and non-equilibrium concentration fluctuations in a critical binary mixture.

When a macroscopic concentration gradient is present across a binary mixture, long-ranged non-equilibrium concentration fluctuations (NCF) appear as a consequence of the coupling between the gradient and spontaneous equilibrium velocity fluctuations. Long-ranged equilibrium concentration fluctuations (ECF) may be also observed when the mixture is close to a critical point. Here we study the interplay between NCF and critical ECF in a near-critical mixture aniline/cyclohexane in the presence of a vertical concentration gradient. To this aim, we exploit a commercial optical microscope and a simple, custom-made, temperature-controlled cell to obtain simultaneous static and dynamic scattering information on the fluctuations. We first characterise the critical ECF at fixed temperature T above the upper critical solution temperature Tc, in the wide temperature range [Formula: see text] °C. In this range, we observe the expected critical scaling behaviour for both the scattering intensity and the mass diffusion coefficient and we determine the critical exponents [Formula: see text], [Formula: see text] and [Formula: see text], which are found in agreement with the 3D Ising values. We then study the system in the two-phase region (T < T c). In particular, we characterise the interplay between ECF and NCF when the mixture, initially at a temperature Ti, is rapidly brought to a temperature T f > T i. During the transient, a vertical diffusive mass flux is present that causes the onset of NCF, whose amplitude vanishes with time, as the flux goes to zero. We also study the time dependence of the equilibrium scattering intensity I eq, of the crossover wave vector q co and of the diffusion coefficient D during diffusion and find that all these quantities exhibit an exponential relaxation enslaved to the diffusive kinetics.

Multicenter study on hepatitis C virus-related cryoglobulinemic glomerulonephritis.

BACKGROUND: Mixed cryoglobulinemia is a multisystem disorder associated strongly with hepatitis C virus (HCV) infection. The kidney frequently is involved, and glomerulonephritis represents the key factor affecting prognosis. METHODS: Clinical, serological, immunogenetic, and morphological data were collected retrospectively from medical records of 146 patients with cryoglobulinemic glomerulonephritis who underwent biopsies in 25 Italian centers and 34 cryoglobulinemic controls without renal involvement. RESULTS: Eighty-seven percent of patients were infected with HCV; genotype 1b was more frequent than genotype 2 (55% versus 43%). Diffuse membranoproliferative glomerulonephritis was the most prevalent histological pattern (83%). Type II cryoglobulin (immunoglobulin Mkappa [IgMkappa]/IgG) was detected in 74.4% of cases. The remainder had type III (polyclonal IgM/IgG) cryoglobulins. A multivariate Cox proportional hazard model showed that age, serum creatinine level, and proteinuria at the onset of renal disease were associated independently with risk for developing severe renal failure at follow-up. Overall survival at 10 years was about 80%. Kaplan-Meier survival curves were worsened by a basal creatinine value greater than 1.5 mg/dL (>133 mumol/L), but were unaffected by sex and HCV infection. Cardiovascular disease was the cause of death in more than 60% of patients. CONCLUSION: Data confirm the close association between mixed cryoglobulinemia and HCV infection and between glomerulonephritis and type II cryoglobulin. Survival profiles are better than previously reported in the literature, probably because of improvement in therapeutic regimens. Causes of death reflect this improvement in survival, with an increased prevalence of cardiovascular events compared with infectious complications and hepatic failure, which were predominant in the past.

Glomerular podocytes contain neuron-like functional synaptic vesicles.

Although patients with chronic renal failure are increasing worldwide, many aspects of kidney biology remain to be elucidated. Recent research has uncovered several molecular properties of the glomerular filtration barrier, in which podocytes, highly differentiated, ramified cells that enwrap the glomerular basement membrane, have been reported to be mainly responsible for filter's selectivity. We previously described that podocytes express Rab3A, a GTPase restricted to cell types that are capable of highly regulated exocytosis, such as neuronal cells. Here, we first demonstrate by a proteomic study that Rab3A in podocytes coimmmunoprecipitates with molecules once thought to be synapse specific. We then show that podocytes possess structures resembling synaptic vesicles, which contain glutamate, coexpress Rab3A and synaptotagmin 1, and undergo spontaneous and stimulated exocytosis and recycling, with glutamate release. Finally, from the results of a cDNA microarray study, we describe the presence of a series of neuron- and synapse-specific molecules in normal human glomeruli and confirm the glomerular protein expression of both metabotropic and ionotropic glutamate receptors. These data point toward a synaptic-like mechanism of communication among glomerular cells, which perfectly fits with the molecular composition of the glomerular filter and puts in perspective several previous observations, proposing a different working hypothesis for understanding glomerular signaling dynamics.

Circulating antibodies recognising oxidatively-modified low-density lipoproteins in patients with IgA nephropathy, membranous glomerulonephritis and focal glomerulosclerosis.

BACKGROUND: Oxidation of low-density lipoproteins (LDL) generates molecular epitopes that play a pathologic role in experimental glomerular diseases and can also elicit an immune response and the generation of anti-oxidatively-modified LDL antibodies. METHODS: We investigated, for the first time in humans, the enhanced induction of LDL oxidation in chronic glomerulonephritis, the presence of circulating antibodies against oxidatively-modified LDL in patients with IgA glomerulonephritis (IgA GN) or with nephrotic syndrome associated with focal glomerulosclerosis (FGS) and primary membranous glomerulonephritis (MGN). The antibody levels were measured by enzyme-linked immunosorbent assay (ELISA) using native and copper-, peroxidase-, hypochlorite-, and peroxynitrite-oxidized LDL. RESULTS: Compared to control subjects, the three groups of patients, particularly the IgA GN patients, had higher serum levels of antibodies recognising LDL oxidised with the four different modalities and higher concentrations of cholesterol in circulating immune complexes. None of these were significantly correlated with any demographic, histological or biochemical laboratory finding. In patients with IgAGN, we investigated the possible confounding effects of cardiovascular risk factors (hypercholesterolemia, hypertension, diabetes and overt atherosclerosis). Although the concentration of cholesterol in circulating immune complexes was significantly higher in patients with cardiovascular risk factors, no significant differences were observed in the level of anti-oxidised-LDL antibodies. This analysis, however, was impossible in FGS and MGN patients because of the high prevalence of hypercholesterolemia in these groups. CONCLUSIONS: These results suggest that IgA GN, MGN and FGS are associated with an enhanced immune response to LDL oxidised with different stimuli mimicking the pro-oxidant environment occurring in vivo, mirrored by the increased levels of specific antibodies, very likely linked to enhanced in vivo LDL oxidation which might participate in glomerular damage and progression.

Which cannulation technique for which patient.

Cannulation of arteriovenous (AV) access is a crucial part of vascular access management in hemodialysis patients. It can significantly affect survival of the AV access, and consequently, it probably influences patient survival. The best type of cannulation technique, rotating site versus constant site (or buttonhole), is currently debated, but the increase in infectious complications observed with the buttonhole technique suggests a prudent use of this technique, restricting it to specific patients. Even in cases with a specific indication, the balance between advantages of the constant site needling and the potentially severe consequences of access related systemic infection should be considered. Educational efforts in improving cannulation skills of dialysis staff are important for improving outcomes, as the proper use of the rotating site technique might still be the best approach to cannulation.

Bleeding, vertebral fractures and vascular calcifications in patients treated with warfarin: hope for lower risks with alternative therapies.

Anticoagulant therapy in patients with atrial fibrillation requires careful evaluation because its benefits i.e. prevention of thromboembolism, must be greater than the risk of bleeding. Patients at higher risk of thrombosis are evaluated through specific scores, such as the CHA(2)DS(2)VASc, coupled with scoring systems for assessing bleeding risks, such as the HAS-BLED score. In addition to bleeding, other risks have been associated with the use of warfarin, including an increased susceptibility to vascular calcifications and fractures caused by a reduction in the levels of vitamin K dependent carboxylated enzymes, matrix Gla-protein (MGP) and bone Gla-protein or osteocalcin (BGP). In fact, while on one side warfarin is used to prevent embolism, on the other hand acting as a vitamin K antagonist it blocks the inhibitory effect of MGP on vascular calcification. Similarly, patients treated with warfarin carry a greater risk of developing osteoporosis and fractures, due to reduced BGP activity. Recently, a new generation of anticoagulant drugs has been developed, such as dabigatran, a direct thrombin inhibitor, and rivaroxaban, a direct factor-Xa inhibitor. They offer an interesting alternative to warfarin, because they do not require frequent blood tests for monitoring while offering similar results in terms of efficacy. Lacking the inhibitory effect on the vitamin K cycle, the consequent side effects can be avoided. If, compared to warfarin treated patients, a lower incidence of vascular calcifications and fractures will be demonstrated, the advantages over warfarin may be even greater, leading to further benefits in terms of morbidity and mortality.